//圆类
public class Circle {
	// 半径
	double radius;
	private final static double Pi = 3.1415926535;

	// 面积
	public double getArea() {
		if (radius > 0) {
			return Pi * radius * radius;
		} else {
			return -1;
		}
	}

	// 面积
	public static double getArea(double radius) {
		if (radius > 0) {
			return Pi * radius * radius;
		} else {
			return -1;
		}
	}

	// 周长
	public double getPerimeter() {
		if (radius > 0) {
			return Pi * radius * 2;
		} else {
			return -1;
		}
	}

	// 周长
	public static double getPerimeter(double radius) {
		if (radius > 0) {
			return Pi * radius * 2;
		} else {
			return -1;
		}
	}
}
